1. Field of the Invention
The present invention generally relates to a voltage regulating circuit, and more particularly, to a voltage regulating circuit capable of improving the undershoot amplitude of a transient output voltage.
2. Description of Related Art
In a general computer system or a server, a voltage regulating circuit is used for providing an appropriate voltage to the CPU (central processing unit) thereof, and the voltage regulating circuit is usually directly plated on the motherboard thereof. The voltage regulating circuit regulates and provides a required voltage, so that the components on the motherboard are able to run with the obtained feed voltage. In addition, in response to a voltage level demand generated and sent by a sensing processor, the voltage regulating circuit detects a voltage identification pin (VID pin) of a microprocessor so as to provide a constant feed voltage to the microprocessor.
However, for the most computer systems and servers, the enterprise voltage regulator down (EVRD) must satisfy a strict testing specification proposed by Intel Co., wherein the most critical and the hardest demand to meet is the overshoot amplitude and the undershoot amplitude of the output voltage of the EVRD during a transient status of load. To satisfy the aforesaid testing specification, a conventional voltage regulating circuit mostly relies on improving the overshoot amplitude of a transient voltage, which can only lower down the overshoot amplitude of a transient voltage without considering the undershoot amplitude problem of a transient voltage; i.e., the conventional voltage regulating circuit is unable to meet the requirement of undershoot amplitude of a transient voltage, and the computer system or the server employing the conventional voltage regulating circuit has a risk of shutdown during the CPU running at a specific frequency.